In recent years, a camera for recognizing an environment around a vehicle such as a passenger car is being developed. In such techniques, by utilizing the features of camera that can sense a two-dimensional image, a recognition method using shape information of an object and a recognition method using motion difference between an object and a background are developed.
A method of Patent Document 1 (Japanese Unexamined Patent Application Publication No. Hei11-317939) realizes accurate tracking by recognizing an object, for example, another vehicle, from an image captured by a camera mounted in one vehicle and predicting motion of a specific point on the other vehicle based on behavior of the one vehicle. This method predicts the specific point moving on the image by recognizing the object and defining the height of the specific point present in the object.